The drought's threat to California's finite supply of groundwater is highlighted in a UC Davis study released Tuesday in Washington, D.C.

Among the major findings reported by the school's Center for Watershed Sciences:

-- The drought -- the third most severe on record -- is responsible for the greatest water loss ever seen in California agriculture, with river water for Central Valley farms reduced by roughly one-third.

-- Groundwater pumping is expected to replace most river water losses, with some areas more than doubling their pumping rate over the previous year.

-- If the drought continues for two more years, pumping ability will slowly decrease, and costs and losses will slowly increase due to groundwater depletion.

-- Overdraft of groundwater is expected to cause additional wells in the Tulare Basin to run dry if the drought continues.

-- Direct costs to agriculture total $1.5 billion (revenue losses of $1 billion and $500 million in additional pumping costs). This net revenue loss is about 3 percent of the state's total agricultural value.

-- The total statewide economic cost of the 2014 drought is $2.2 billion.

-- Five percent, of irrigated cropland is going out of production in the Central Valley, Central Coast and Southern California due to the drought.

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-- Agriculture on the Central Coast and in Southern California will be less affected by this year's drought, with about 19,150 acres fallowed, $10 million in lost crop revenue and $6.3 million in additional pumping costs.

-- The drought is likely to continue through 2015, regardless of El Niño conditions.

-- Consumer food prices will be largely unaffected. Higher prices at the grocery store of high-value California crops like nuts, wine grapes and dairy foods are driven more by market demand than by the drought.